This invention generally relates to fuel deoxygenation system for removing oxygen from a fuel stream. More particularly, this invention relates to an electrochemical device for generating a partial oxygen pressure differential for removing oxygen from the fuel stream.
It is common practice to use fuel as a cooling medium for various systems onboard an aircraft. The usable cooling capacity of a particular fuel is limited by the formation of coke, which in turn is dependent on the amount of dissolved oxygen present within the fuel. It has been determined that decreasing the amount of dissolved oxygen present within the fuel reduces the formation of insoluble products referred to as “coke” or “coking”. Further, the removal of dissolved oxygen from the fuel increases the temperature at which fuel can be heated without generating the autooxidative reactions that cause “coking”.
U.S. Pat. Nos. 6,315,815 and 6,709,492 assigned to Applicant, disclose devices for removing dissolved oxygen using a gas-permeable membrane disposed within the fuel system. As fuel passes along the permeable membrane, oxygen molecules in the fuel dissolve into the membrane and then diffuse across it and are removed. A vacuum or oxygen partial pressure differential across the permeable membrane drives oxygen from the fuel, which is unaffected and passes over the membrane.
The creation of a vacuum proximate the permeable membrane requires a vacuum pump or other device. Generating a vacuum to produce the required oxygen partial-pressure differential across the permeable membrane can result in a total pressure differential that requires a rather bulky support structure for the permeable membrane. Further, the vacuum pump itself is bulky and requires a substantial amount of energy that is provided by an energy conversion device. A strip gas, such as nitrogen can be utilized for generating the desired oxygen partial pressure differential. However, the use of a strip gas requires a stored supply of a non-oxygen containing gas. As appreciated, the vacuum pump, increased support structure and stored strip gas all add weight and complexity to a fuel delivery system.
Accordingly, it is desirable to design and develop a system and device with reduced weight, structure and complexity for removing oxygen from a jet fuel stream.